JP2003328469A - Ceiling board with noncombustibility, sound absorption and radio wave absorption - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively prevent an indoor radio communication disturbance by using a lightweight ceiling board which has not only adequate flexural strength, noncombustibility, sound absorption and heat insulating properties but also appropriate absorption of a radio wave for indoor radio communication. <P>SOLUTION: The radio wave-absorbing ceiling board is obtained by applying wet sheet making to water-dispersed slurry serving as a mixture in which rock wool, beaten pulp, a binder, a flocculant, natural mineral fibers and carbon fibers are mixed together in a specified range. Otherwise, the radio wave- absorbing ceiling board is obtained by sticking metallic foil on the backside of the ceiling board which is obtained by applying the wet sheet making to the water-dispersed slurry. The indoor radio communication disturbance is prevented by using either of the ceiling boards. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceiling which is lightweight and has sufficient bending strength, nonflammability, sound absorption and heat insulation properties, radio wave absorption, and noncombustible sound absorption and radio wave absorption for the purpose of design. The present invention relates to a plate, a non-combustible radio wave absorbing ceiling plate having a metal foil attached to the ceiling plate to improve radio wave shielding properties, and a ceiling plate having a back surface coated with an organic paint containing carbon fiber.

[0002]

2. Description of the Related Art The spread of wireless communication devices represented by mobile phones and PHS is remarkable, and wireless communication devices used in wireless data communication networks called wireless LANs are rapidly spreading in offices, stores, factories, warehouses, etc. I'm doing it. When using such a wireless communication device in a specific indoor space such as an office, it is possible to prevent intrusion of noise radio waves from the outside,
There is known a technique of constructing a radio wave shield made of metal foil, mesh, conductive fiber or the like for the purpose of preventing indoor information from leaking to the outside.

However, when such a radio wave shield is constructed, the radio wave reflectivity in the room is increased, and the radio waves transmitted from the wireless communication device are transmitted from the inner wall, ceiling, floor, and steel furniture fittings. Reflected waves with different phases arrive at the receiving terminal, or multiple reflected waves arrive from the ceiling, wall, floor, etc. and the receiver cannot recognize them as normal signals, resulting in abnormal communication time. There is a problem that it becomes long or communication is lost. In addition, even without intentionally constructing the radio wave shield, offices in recent years may use metal deck plates on the ceiling and floor surfaces, or may use metal double floor panels on the floor surface. In many cases, the upper and lower surfaces are often in a radio wave reflection environment. In many cases, a steel partition wall is also used as the wall surface, and the wall surface is often used as a radio wave reflector.

In such an indoor environment, as in the case where the above-mentioned radio wave shield is intentionally constructed, when wireless communication equipment is used, transmission abnormalities due to reflected waves with different phases and reflected waves arriving with a delay in time are generated. A communication failure may occur due to the influence. As a countermeasure against this phenomenon, it is effective to install a member that suppresses the reflection of radio waves in the interior material of the room, and conventionally, a cement material or a gypsum board containing ferrite tile or ferrite or a conductive material has been used. There is. In addition, a construction method has been proposed in which a felt-shaped electromagnetic wave absorber is integrated with the back surface of a ceiling or floor or a base board.

[0005]

However, in addition to the complexity of the conventional construction method, the cement material or gypsum board containing ferrite tile, ferrite or conductive material has a large specific gravity, which makes the construction troublesome. On top of that, it is expensive. In addition, to prevent the reflection of radio waves, if it is assumed that the floor and wall parts of the interior building material will be constructed with a radio wave absorber, then in many cases, a steel desk will be installed on the floor first. As a result, the floor becomes a radio wave reflector, and in many cases the radio wave absorption effect of the radio wave absorber installed on the floor is impaired. Also, when a radio wave absorber is installed on the wall surface, there are many cases where a steel bookcase or locker is installed on the front surface of the wall after the installation.
As a result, most of the wall surface becomes a radio wave reflector, often impairing the effect of the radio wave absorber.

On the other hand, when the electromagnetic wave absorber is installed on the ceiling surface, there is no case where the electromagnetic wave reflector is installed on the indoor side of the ceiling surface after installation, and a desk or bookcase made of steel is installed. Therefore, even if the usage situation in the room changes, the electromagnetic wave absorption performance of the ceiling surface is less likely to be impaired. Also wireless L
The transmission / reception device of the AN is often installed and used on a desk or a personal computer on the desk. In many cases, the transmitted radio waves are reflected by the ceiling surface. It is preferable to install a radio wave absorber.

However, in the above-mentioned conventional construction method, since the ferrite tile, the ferrite-containing gypsum board and the like are materials having a high specific gravity, it is not only difficult to carry out the construction, but also the cost is high and the color of the board is black, and There is also a problem in terms of earthquake resistance.

The present invention has been made in view of the above circumstances, and is a lightweight, sufficient bending strength, nonflammability, and sound absorbing property as an interior ceiling plate which is an optimum portion for solving the communication problem of wireless LAN. To obtain a ceiling plate that has heat insulation properties, has suitable electromagnetic wave absorption performance conditions, and is also designed.
Another object of the present invention is to obtain an interior ceiling plate having a radio wave shielding property added and improved by applying a metal foil to the ceiling plate.

[0009]

[Means for Solving the Problems] The desired ceiling plate for interior is rock wool for imparting incombustibility, sound absorption and heat insulation, and beaten pulp and organic matter commonly called gel for imparting strength and water resistance. Binders, coagulants to improve the collecting properties and strength of the binder during papermaking, natural mineral fibers to improve the dimensional stability and appearance / surface smoothness / strength of the panel, and water repellency. An organic water repellent for imparting,
It has been found that the mixture can be obtained by dispersing a mixture containing carbon fiber for imparting radio wave absorption and water to form a slurry, and manufacturing the slurry by wet papermaking.

That is, the present invention relates to rock wool 67-92w.
t%, beaten pulp 0.5 to 8% by weight, binder 2 to 13% by weight made of organic resin, coagulant 0.15 to 1% by weight made of organic polymer resin and inorganic salt, natural mineral fiber 0.
A thickness of 1 to 30 mm, which is obtained by wet-making a water-dispersed slurry of a mixture containing 5 to 10 wt% and 0.02 to 1 wt% of carbon fibers having a fiber length of 1 to 30 mm.
The ceiling plate of will be the means for solving the problem.

As an invention aimed at designability, rock wool 67 to 92 wt% and beaten pulp 0.5 to 8 w
t% and 2 to 13 wt% of a binder made of an organic resin,
Coagulant 0.15 consisting of organic polymer resin and inorganic salt
Layer obtained by wet papermaking of a water-dispersed slurry of a primary mixture containing 1 to 1 wt% and natural mineral fibers 0.5 to 10 wt%, and carbon fiber having a fiber length of 1 to 30 mm with respect to the primary mixture Is also used as a means for solving the problems, and a ceiling plate having a thickness of 1 to 30 mm and having a non-combustible sound absorbing and radio wave absorbing property, which is composed of a layered structure obtained by wet-papermaking a water-dispersed slurry of a secondary mixture further containing 0.02 to 1 wt% To do.

The carbon fiber compounded in the non-combustible sound absorbing and electromagnetic wave absorbing ceiling board is pretreated with 0.5 to 0.5 in water.
~ 2wt% input, rotation speed is 100 ~ 4
Stirring for 0.5 to 3 minutes with a mixer of 00 rpm is also a suitable means.

It is also preferable to add an additive such as an inorganic filler in an amount of 50 wt% or less in the form of replacing the rock wool blended as the main component of the ceiling plate having the non-combustible sound absorbing and radio wave absorbing property.

In order to improve the electromagnetic wave shielding property of the non-combustible sound absorbing electromagnetic wave absorbing ceiling plate and the electromagnetic wave absorbing property due to the resonance phenomenon of reflected electromagnetic waves, a metal foil is adhered to the back surface of the non-combustible absorbing electromagnetic wave absorbing metallic foil. A ceiling plate is also a suitable means.

On the other hand, the radio wave absorbing performance is effectively exhibited under the condition that no metal foil or metal plate is arranged on the back surface of the non-combustible sound absorbing radio wave absorbing ceiling plate, that is, the radio wave reflected by the metal foil or metal plate or the like. When the electromagnetic wave absorption caused by the resonance phenomenon is not added, a suitable electromagnetic wave absorption performance can be obtained by setting the compounding ratio of the carbon fiber having a fiber length of 1 to 30 mm to 0.08 to 0.4 wt%.

Even if the above-mentioned carbon fiber content is as low as 0.04 to 0.08 wt%, the carbon fiber content on the back surface of the ceiling plate is higher than the content, preferably 1.0 to 1
By applying the organic coating material containing carbon fiber in an amount of 5.0 wt% in an amount of 100 to 3000 g / m ² , even under the condition that no metal plate or metal plate is arranged on the back surface of the ceiling plate, It is possible to obtain the same preferable radio wave absorption performance as described above.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION A non-combustible sound absorbing and electromagnetic wave absorbing ceiling plate of the present invention will be described below. The rock wool constituting the present invention includes SiO ₂ 35 to 55 wt% and Al ₂ O ₃ 10 to
20wt%, MgO 5-40wt%, CaO 5-40w
t%, FeO 0 to 10 wt%, Na ₂ O, K ₂ O, TiO
₂ , a raw material mineral mixture containing 0 to 10 wt% of a minor component such as MnO is melted in a cupola furnace or an electric furnace, and is fiberized by a blowing method or a spinning method using a high-speed rotating body. The fibers are wool-like and have fiber lengths in the range of several millimeters to tens of millimeters.

With respect to the blending ratio of the rock wool, the range of 67 to 92 wt% is appropriate in relation to the nonflammability, the sound absorbing property, and the strength, and if it is less than 67 wt%, the organic binder ratio becomes relatively large. , Nonflammability and sound absorption are impaired,
If it exceeds wt%, the ratio of the organic binder becomes relatively small and the bending strength as the interior ceiling plate becomes insufficient.

The mixing ratio of the beaten pulp is based on the relationship between nonflammability, drainage during papermaking, and strength as an interior ceiling plate.
The range of 0.5 to 8 wt% is appropriate, and if it is less than 0.5 wt%, the strength of the ceiling board is insufficient, and if it exceeds 8 wt%, the incombustibility and the drainage property at the time of manufacturing deteriorate, and the fireproofness and productivity are impaired. It will be.

Materials used as the organic binder include starch, polyvinyl alcohol, polyethylene,
Powder of paraffin, phenol resin, melamine resin,
Thermosetting powder resin such as epoxy resin or acrylic resin,
Examples thereof include organic binders such as emulsions of modified acrylic resins, polyvinyl acetate, ethylene / acetic acid copolymer resins, polyvinylidene chloride resins, modified polyvinylidene chloride resins, epoxy resins and urethane resins. The blending amount of these organic binders is appropriately 2 to 13 wt% in terms of the relationship between incombustibility and strength, and exceeding 13 wt% impairs incombustibility, while less than 2 wt% results in insufficient bending strength. However, by adding aluminum hydroxide in the form of replacing rock wool, the organic binder is added to 13 to 2
0 wt% can be added.

Since the present invention is manufactured by a wet papermaking method, it is necessary to add a small amount of a coagulant such as polyacrylamide or a sulfuric acid band that effectively retains the organic binder. The blending amount of the polymer flocculant is preferably in the range of 0.15 to 1 wt% from the viewpoint of strength effect and nonflammability.

Further, in the present invention, it is necessary to add natural mineral fibers such as attapulgite and sepiolite for the purpose of improving strength, dimensional stability, and moisture resistance. In relation to the drainage and the strength, which are related to the productivity during wet papermaking, 0.5 to
The range of 10 wt% is appropriate, and if it exceeds 10 wt%, the drainage time becomes long and the productivity is impaired, and if it is less than 0.5 wt%, the dimensional stability and the moisture flexing resistance become insufficient.

In the present invention, it is necessary to add a small amount of water repellent such as wax emulsion and silicone resin emulsion in order to impart water repellency. The mixing ratio of the water repellent is
0.1-0.5wt due to the relationship between water repellency, strength, and noncombustibility
% Range is preferred.

In the constitution of the present invention, a fibrous conductive substance is blended as a component for imparting radio wave absorption performance. The fibrous conductive material is preferably PAN-based or pitch-based carbon fiber and has a fiber length of 1 to 30 mm.
Examples of such representatives include Zyrus manufactured by Osaka Gas Co., Ltd., trading card manufactured by Toray Co., Ltd., and Bethfight manufactured by Toho Rayon Co., Ltd. The longer the fiber length of carbon fiber, the better the electromagnetic wave absorption performance with a small blending amount, while the carbon fiber becomes entangled when dispersed and stirred in water during papermaking molding, resulting in poor dispersibility and deterioration of electromagnetic wave absorption performance. As the fiber length is 30
mm or less is preferable. When the thickness is less than 1 mm, there is no problem in dispersibility, but it is difficult to obtain the dielectric loss effect, which is the principle of electromagnetic wave absorption, and the electromagnetic wave absorption performance deteriorates.

The mixing ratio of the carbon fiber is
It was found that a good radio wave absorption performance is exhibited at 0.02 wt% or more. Here, if it exceeds 1 wt%, the characteristics of the radio wave reflectance will be improved too much and the radio wave absorption performance may be deteriorated, so the range of 0.02 to 1 wt% is preferable. It is presumed that the blended carbon fiber acts as a dielectric, causes a loss of radio wave energy due to a dielectric loss in a frequency band of gigahertz or higher, and exhibits a desired radio wave absorption performance.

The non-combustible sound absorbing and electromagnetic wave absorbing ceiling plate of the present invention is
Rock wool, an organic binder, a mixture containing a binding aid and carbon fiber is dispersed in water, a net or a Fourdrinier type, a wet mat is made into paper by a paper making apparatus such as a funnel former, and dried and cured, It is obtained by cutting and cutting into an arbitrary shape. Although the main constituent components and the production method of the present invention are as described above, it is possible to add a small amount of a flame retardant or an inorganic substance to the organic binder for the purpose of improving fire resistance and cost reduction.

The ceiling plate of the present invention has a thickness of 1 to 30 mm, preferably 9 to 19 mm. The bulk density of the ceiling plate is preferably 0.3 to 0.5 g / cm ³ .

The non-combustible sound absorbing and electromagnetic wave absorbing ceiling board of the present invention includes a laminated ceiling board composed of at least two layers of a layer containing no carbon fiber and a layer containing carbon fiber. The ceiling board is rock wool 67-9
2 wt%, beaten pulp 0.5-8 wt%, binder 2-13 wt% made of organic resin, coagulant 0.15-1 wt% made of organic polymer resin and inorganic salt, and natural mineral fiber 0 First, a primary mixture of 0.5 to 10 wt% was formed into a layer, and the fiber length of 1 to 1 was added to the mixture.
An aqueous dispersion slurry of a secondary mixture containing 0.02 to 1 wt% of 30 mm carbon fiber is layered to form a layer, or the carbon fiber is first added to 0.02.
To form a layered layer of a water-dispersed slurry of the secondary mixture obtained by blending in an amount of 1 wt% to form a layered layer of the water-dispersed slurry of the primary mixture. Can be obtained.

When the carbon fiber is contained, it may not be preferable because the black color of the fiber appears on the surface in a linearly dispersed state although it depends on the blending amount thereof, which is an obstacle particularly to a product having a pure white surface. Becomes Therefore, it is preferable that the layer containing no carbon fiber is laminated on the front side, that is, the side facing the room in the case of ceiling construction, and the layer containing carbon fiber is the back side. As the manufacturing method, as described above, a layer containing carbon fibers may be formed first, or a layer not containing carbon fibers may be formed first. Either a layer containing carbon fibers or a layer not containing carbon fibers may be used. It is preferable to continuously produce and and to laminate and manufacture. The layer containing carbon fibers is preferably designed as a back surface side because of its design. Although the thickness of each layer is not particularly limited, it is preferable in view of dispersibility of the carbon fiber that the layer not containing carbon fiber is usually made thin and the layer containing carbon fiber is made thicker.

Since the carbon fibers are separated from the state in which the fibers are bundled, the carbon fibers are insufficiently dispersed by simply mixing them in water at the same time as other compounding ingredients and stirring them to obtain good electromagnetic wave absorption characteristics. Absent. As a result of intensive studies made by the inventors with respect to such a problem, as a result of adding 1 to 30 mm of carbon fiber in water to 0.5
~ 2wt% input, rotation speed is 100 ~ 4
It was found that a good dispersion state was achieved by stirring for 0.5 to 3 minutes with a mixer of 00 rpm. By mixing and using this with other compounding components, it is possible to obtain a non-combustible sound absorbing and electromagnetic wave absorbing ceiling plate that exhibits suitable electromagnetic wave absorbing performance.

In the composition of the present invention, an inorganic filler such as aluminum hydroxide, pearlite or shirasu balloon may be blended for the purpose of adjusting nonflammability and density. The blending ratio of aluminum hydroxide is preferably 50 wt% or less in the form of replacing rock wool. If it exceeds 50 wt%, the drainage time becomes long, the productivity at the time of molding is deteriorated, and the strength is lowered. Perlite and shirasu balloons are also used in the form of replacing rock wool, and are preferably 30 wt% or less in terms of density and strength.

When a metal foil is attached to the back surface of the non-combustible sound absorbing and radio wave absorbing ceiling board, in addition to the performance as the non-combustible sound absorbing and radio wave absorbing ceiling board, the ability to shield radio waves should be provided. You can Regarding the electromagnetic wave absorption performance, since the electromagnetic wave absorption performance caused by the resonance phenomenon of the metal foil reflected electromagnetic waves is additionally improved, it is effective in combination with the electromagnetic wave shielding performance, and it is economical to use the ceiling plate integrally molded with the back metal foil. It is also a good idea from the standpoint of workability. In addition, the back surface referred to in the specification of the present application refers to the interior side of the ceiling plate after construction as the front surface and the back side of the ceiling as the back surface. When laminating aluminum foil, metal foil such as steel foil to the ceiling board, it is bonded with an adhesive such as acrylic resin, vinyl acetate resin, ethylene resin, vinyl resin, urethane resin, epoxy resin, synthetic rubber, etc. I do. The metal foil is adhered to the back side of the ceiling plate. Considering surface protection and panel workability, the thickness of the metal foil is 5
To 200 μm, and more preferably 50 to 100 μm
Select a soft metal foil.

On the other hand, with respect to the resonance phenomenon, the result of a study on the more effective radio wave absorption condition will be described in detail below. An electromagnetic wave reflector such as aluminum foil is provided on the back surface of the electromagnetic wave absorber, and the phase of the incident wave and the reflected wave is inverted due to the dielectric magnetic permeability effect of the electromagnetic wave absorber, causing electromagnetic wave energy loss. In the case of a method of obtaining performance, the radio wave reflection layer is an essential component. However, since the radio wave absorber provided with these radio wave reflectors on the back surface has a structure in which metal foils such as aluminum foils are laminated, the cost is increased. Further, since a metal body such as aluminum may be corroded, when the radio wave absorber is adhered to another structure, adhesion failure with the resin adhesive may occur.

Further, when the plasterboard is thrown up and the rock wool board is put up with makeup, if the ceiling board is to have an electromagnetic wave absorbing performance, one method is to mix ferrite or conductive fiber inside the plasterboard. However, there is a method of using a radio wave absorption gypsum board with an aluminum foil on the back surface and a non-combustible absorbent ceiling board on the bottom surface using a tacker and an adhesive. As a second method, the composition of the gypsum board is a general gypsum board composition, an aluminum foil is attached to the lower surface of the gypsum board, and a non-combustible sound absorbing and electromagnetic wave absorbing decorative ceiling board containing ferrite and conductive fibers is used as a tacker and an adhesive. There is a method of construction using. The third method is to throw away a gypsum board that does not have a general radio wave absorption property and attach a metal foil such as aluminum foil to the back surface of a decorative non-combustible sound absorbing radio wave absorption ceiling plate mixed with ferrite and conductive fibers. It is conceivable that the plasterboard is attached to the plasterboard using an adhesive and a tacker.

However, in the first method, the cost of the gypsum board becomes high by laminating the metal foil such as the aluminum foil. In the second method, in addition to the fact that the gypsum board is also high in cost, a metal foil such as aluminum foil is interposed between the gypsum board and the decorative ceiling board, so that the metal foil corrodes to adhere to the decorative ceiling board. The strength is reduced and the decorative ceiling board is easily peeled off. In the third method,
Although the cost of plasterboard does not increase, in addition to the high cost of the radio wave absorption decorative ceiling plate, the adhesive force with the decorative ceiling plate decreases due to the corrosion of the metal foil due to the same reason as in the second method. Plate easily peels off. In addition, for the so-called system ceiling, such as the direct tensioning method without throwing out the plaster board, the method of placing the decorative ceiling board on the ceiling metal fitting (lay-in method), and the method of inserting the metal fitting into the small edge of the decorative ceiling board and supporting it It goes without saying that the radio wave absorption gypsum board of can not be used. In addition, a non-combustible sound absorbing and electromagnetic wave absorbing ceiling board in which a metal foil is placed on the back surface of the decorative ceiling board has become expensive and has not yet been put into general use.

Based on the above situation, various examinations were made on the results of the electromagnetic wave absorption performance test.
Since the metal plate is installed on the back surface of the ceiling plate of the test body, it was found that the absorption characteristic due to so-called resonance due to radio wave reflection is added, which is also a cause of exhibiting the preferable absorption performance. So, in the conventional electromagnetic wave absorption test, carbon fiber exhibits good electromagnetic wave absorption performance at a blending amount of 0.02 wt% or more, but if there is no electromagnetic wave reflector such as a metal foil on the back surface, it will be 0.02 wt%. % To 0.08
It has been found that when the compounding amount is less than wt%, the radio wave absorption performance is deteriorated and does not reach a more desirable and preferable absorption performance.

On the other hand, from 0.4 wt% to 1.5 wt%, a certain level of radio wave absorption performance is exhibited, but as the compounding amount is increased from 0.4 wt%, the radio wave reflection characteristics become stronger,
As a result, there is a disadvantage that the absorption performance is reduced. On the other hand, if it exceeds 1.5 wt%, the radio wave reflectance of the panel becomes too strong and the radio wave absorption performance is significantly deteriorated. Therefore, by setting the blending ratio of the carbon fibers having a fiber length of 1 to 30 mm in the range of 0.08 to 0.4 wt%, it is possible to obtain a desired result without attaching a metal foil to the back surface of the ceiling plate having non-combustible sound absorbing and electromagnetic wave absorbing properties. It was found that it was possible to perform the preferable radio wave absorption of the above.

Further, as described above, if the carbon fiber content is low, it is difficult to obtain the desired suitable absorption performance without a radio wave reflector such as a metal foil on the back surface. However, even with such a low content, It has been found that a desired and suitable radio wave absorption performance can be obtained by applying an organic coating material containing a larger amount of carbon fibers on its back surface in an amount of 100 to 3000 g / m ² . It is presumed that since the carbon fiber layers having different blending ratios are adjacent to each other, the resonance effect is increased between both layers and the absorption characteristics are improved. further,
Since the amount of carbon fiber on the front side is small,
It is also aesthetically advantageous.

The carbon fiber content on the surface side is preferably 0.08 wt% or less, more preferably 0.04 wt% or less.
Is about 0.08 wt%, and the content of carbon fiber in the organic coating on the back side is preferably 1.0 wt% or more,
More preferably, it is 1.0 to 15.0 wt%.

As the organic paint of the present invention, a vinyl acetate emulsion paint is preferably used, and examples thereof include polyvinyl acetate emulsion paint (PC coat), polyvinyl alcohol emulsion paint, polyvinyl acetal emulsion paint and the like. . Examples of the carbon fiber to be blended in the organic coating material include the same as those described above, and the fiber length thereof is not particularly limited, but 0.1 to 30 mm is preferable, and uniform dispersion and mixing are easy. From the standpoint of sex, 0.5-2 mm is particularly preferable.

[0041]

EXAMPLES Hereinafter, the non-combustible sound absorbing and electromagnetic wave absorbing ceiling board and the metal foil-clad ceiling board of the present invention are shown in Examples 1 to 11 and Comparative Examples 1 to 2 together with Table 1 and Table 2, and Examples 12 to 19, Comparative Example 3 and Reference Examples 1 and 2 will be described together with Tables 3 and 4, and Example 20 will be described together with Table 5.

<Example 1> 41 wt% SiO ₂ , CaO
Steel slag rock wool 89.6 wt% having a fiber length of 100 to 500 μm and composed of 36 wt%, MgO 6 wt%, Al ₂ O ₃ 12 wt%, and other minor components such as Na ₂ O and K ₂ O of 5 wt%, and water. 1 wt% of beaten pulp dispersed in and refined with a refiner, 5.5 wt% of starch, 2.85 wt% of attapulgite disintegrated by dispersing in water, 1
0.2% by weight of polyacrylamide aqueous solution (based on solid content), 0.6% by weight of aluminum sulfate, 1% by weight in water as a pretreatment, and agitated with a mixer for 2 minutes at a rotation speed of 200 rpm. Made, fiber length 4mm
Carbon fiber (Osaka Gas Co., Ltd .; Zyrus)
0.25 wt% (solid content basis) is added and mixed, and dispersed by a mixer to prepare an aqueous slurry having a concentration of about 5 wt%. The slurry is made into paper by a Fourdrinier paper making machine and dehydrated and dried to produce a master plate. Further, the surface of the original plate was cut to obtain a panel A of an interior ceiling plate having a plate thickness of 12 mm and a bulk density of 0.4 g / cm ³ . Table 1 shows the strength, fire resistance, heat resistance, sound absorption rate, radio wave shielding performance, radio wave absorbing performance, etc. of panel A.

<Example 2> The carbon fiber blending ratio of Example 1 was 0.025 wt% and the rock wool blending ratio was 89.825 wt%. Panel B was obtained. Panel B
Table 1 also shows the performance and the like.

Example 3 The carbon fiber blending ratio of Example 1 was 0.33 wt%, the rock wool blending ratio was 89.52 wt%, and the other conditions were the same as in Example 1 except that the bulk density was 0. A panel C of an interior ceiling plate was obtained so as to have a weight of ³ g / cm ³ . Table 1 shows the performance of panel C
Also shown in.

<Example 4> The carbon fiber content of Example 1 was 0.3 wt% and the rock wool content was 89.55 wt%. Panel D was obtained. Table 1 also shows the performance and the like of panel D having a plate thickness of 9 mm whose surface is cut.

Example 5 The carbon fiber blending ratio of Example 1 was 0.15 wt% and the rock wool blending ratio was 89.7 wt%. Panel E was obtained. Table 1 also shows the performance and the like of the panel E having a plate thickness of 15 mm whose surface is cut.

<Example 6> The mixing ratio of carbon fiber of Example 1 was 0.22 wt%, the mixing ratio of rock wool was 89.63 wt%, and the bulk density was 0 under the same setting conditions as in Example 1 except for the above. A panel F of an interior ceiling plate was manufactured so as to have a weight of 0.5 g / cm ³ . The performance of Panel F is also shown in Table 1.

<Example 7> The carbon fiber of Example 1 has a length of 1 mm, a compounding ratio of 0.4 wt%, a rock wool compounding ratio of 89.45 wt%, and other conditions are the same as those of Example 1. In the above, panel G of the ceiling plate for interior was manufactured. The performance of Panel G is also shown in Table 1.

<Example 8> The carbon fiber of Example 1 has a length of 12 mm and a compounding ratio of 0.18 wt%.
Panel H of the ceiling plate for interior is made under the same setting conditions as in Example 1 except that the mixing ratio of rock wool is 89.67 wt%.
Was manufactured. The performance of the panel H is also shown in Table 2.

Example 9 A soft aluminum foil having a thickness of 50 μm is attached to the back surface of the panel obtained in Example 1 with an ethylene vinyl acetate-based adhesive, and a panel I of an aluminum foil-attached interior ceiling board is attached. Manufactured. Table 2 also shows the performance and the like of the panel I laminated with aluminum foil.

<Example 10> Rock wool 85.95w
t%, beaten pulp 3 wt%, polyvinyl alcohol 7 w
A mixture of t%, attapulgite 3% by weight, 15% concentration polyacrylamide aqueous solution 0.2% by weight (solid content basis), and aluminum sulfate 0.6% by weight was added at a rate of 1% by weight into water as a pretreatment, and 200 revolutions / Fiber length 4 mm, stirred with a mixer for 2 minutes at a rotation speed of 1 minute
Carbon fiber (Osaka Gas Co., Ltd .; Zyrus)
0.25 wt% (solid content basis) is added and dispersed by a mixer to prepare an aqueous slurry having a concentration of about 5 wt%. The slurry is made into paper by a Fourdrinier paper making machine and dehydrated and dried to produce a master plate. Further, the surface of this original plate was cut to obtain a panel J of a 12 mm-thick interior ceiling plate having a sufficient strength as an interior ceiling plate. Table 2 shows the performance of panel J such as strength, fire resistance, thermal resistance, sound absorption coefficient, radio wave shielding performance, and radio wave absorbing performance.

<Embodiment 11> Rockwool 60.95w
t%, beaten pulp 3 wt%, polyvinyl alcohol 7 w
t%, attapulgite 3 wt%, 15% concentration polyacrylamide aqueous solution 0.2 wt% (solid content basis), aluminum sulfate 0.6 wt%, aluminum hydroxide 25 w
Carbon fiber having a fiber length of 4 mm (manufactured by Osaka Gas Co., Ltd.) was added to a mixture composed of t% as a pretreatment in water at a rate of 1 wt% and stirred with a mixer for 2 minutes at a rotation speed of 200 rpm. (Zyrus) is added to 0.25 wt% (solid content basis) and dispersed by a mixer to prepare an aqueous slurry having a concentration of about 5 wt%. The slurry is made into paper by a Fourdrinier paper making machine and dehydrated and dried to produce a master plate. Further, the surface of this original plate was cut to obtain a panel K of an interior ceiling plate having a plate thickness of 12 mm and a bulk density of 0.45 g / cm ³ , which has sufficient strength as an interior ceiling plate. Table 2 shows the strength, fire resistance, heat resistance, sound absorption coefficient, radio wave shielding performance, radio wave absorbing performance, etc. of panel K.

Comparative Example 1 Rock wool 90.25 wt
%, Beaten pulp 1 wt%, starch 5.5 wt%, attapulgite 2.85 wt%, 15% polyacrylamide aqueous solution 0.2 wt% (based on solid content), aluminum sulfate 0.6 wt% is mixed with a mixer, An aqueous slurry with a concentration of about 5 wt% is prepared. The slurry was made into paper by a Fourdrinier paper making machine, dehydrated and dried to obtain a panel L of an interior ceiling plate having a plate thickness of 12 mm. Table 2 shows the strength, fire resistance, thermal resistance, sound absorption coefficient, radio wave shielding performance, radio wave absorbing performance, etc. of the panel L.

Comparative Example 2 88.35 wt of rock wool
%, Beaten pulp 1 wt%, starch 5.5 wt%, attapulgite 2.85 wt%, 15% polyacrylamide aqueous solution 0.2 wt% (solid content basis), aluminum sulfate 0.6 wt%, carbon fiber of 4 mm fiber length (Osaka A mixture consisting of 1.5 wt% of Gas Co., Ltd .; Zyrus) is dispersed by a mixer to prepare an aqueous slurry having a concentration of about 5 wt%. The slurry is made into paper by a Fourdrinier paper making machine and dehydrated and dried to produce a master plate. Further, the surface of this original plate was cut to obtain a panel M of a 12 mm-thick interior ceiling plate having a sufficient strength as an interior ceiling plate. Table 2 shows the strength, fire resistance, thermal resistance, sound absorption coefficient, radio wave shielding performance, radio wave absorbing performance, etc. of the panel M.

[0055]

[Table 1]

[0056]

[Table 2]

<Evaluation and Measurement Methods in Tables 1 and 2> Bending Strength: According to JIS A 1408 (No. 5 test piece) method. Thermal resistance: According to JIS A 1420 method. Fireproof performance: According to JIS A 1321 method. Sound absorption coefficient: According to JIS A 1409 (reverberation room) method. Radio wave shielding performance: A test body having a thickness of 9 to 15 mm and length and width of 400 mm × 400 mm for each test is installed between the radio wave transmitting antenna and the receiving antenna, and the transmission level is measured by the time domain method. The transmission coefficient was calculated as a radio wave shielding performance by comparing with the transmission level when the test body was not installed. Electromagnetic wave absorption performance: In accordance with the "Radioelectric wave absorber performance evaluation measurement method" being studied by the Japan Institute of Architecture, thickness of each test 9
The reflection coefficient was measured by the free space time domain method using a test piece having a length of 15 mm and a length of 400 mm × 400 mm and a metal plate having a length of 400 mm × 400 mm bonded to the back surface of the test body. The reflection coefficient was calculated by comparing it with the reflection level of the metal plate alone and used as the electromagnetic wave absorption performance.

<< Comparison between Examples of Tables 1 and 2 and Comparative Examples >> Regarding the bending strength, all show the suitability value as an interior ceiling board. 2. Regarding heat resistance, they all show sufficient heat insulating properties, and there is no significant difference. 3. Regarding fire resistance, Examples 1 to 9 and Example 11,
And Comparative Examples 1 and 2 are nonflammable, and Example 10 is quasi nonflammable and passes. 4. Regarding the sound absorption coefficient, in each of Examples 1 to 11 and Comparative Examples 1 and 2, an appropriate sound absorption coefficient is shown and there is no significant difference. 5. The radio wave shielding performance is shown in Examples 1 to 8 and 10 to 10.
Although 11 and Comparative Example 2 show a shielding performance of 2 to 5.5 dB, they do not have sufficient performance as a general radio wave shielding material. In Example 9, the shielding performance of 31 dB or more is shown, and the performance of 30 dB or more, which is sufficient performance as a general radio wave shielding material, is satisfied. Comparative Example 1 does not show radio wave shielding performance. 6. Regarding the radio wave absorption performance, in Examples 1 to 11, 6 to 15 dB at 2.45 GHz and 6-1 at 5.1 GHz.
2 dB is shown, which has sufficient absorption performance as a communication failure countermeasure in wireless communication in an office or the like in the 2.4 GHz band and the 5 GHz band used for the wireless LAN system. On the other hand, in the case of Comparative Example 1 in which the carbon fiber as the conductive material is not mixed, the absorption performance is not obtained and the above conditions are not satisfied. Further, in Comparative Example 2, since the carbon fiber is highly mixed, it is affected by radio wave reflection and does not show sufficient absorption performance.

In each of Examples 1 to 11 and Comparative Examples 1 and 2, a test piece was attached to a metal plate in accordance with the "radio wave absorber performance evaluation measurement method" being studied by the Japan Institute of Architecture. Measuring the radio wave absorption. Therefore, the electromagnetic wave absorption performance is measured in a state in which the electromagnetic wave absorption performance due to resonance and the electromagnetic wave absorption performance due to the internal loss of the test object itself are mixed, and the test object itself in the measurement of the electromagnetic wave absorber without the electromagnetic wave reflector on the back surface. It has been found that it is difficult to measure the electromagnetic wave absorption performance due to the internal loss of. The present inventor, in order to more accurately measure the internal absorption characteristics of the test body, to more clearly express the difference with the absorption performance due to the resonance phenomenon,
As a result of diligent study, it was found that the occurrence of resonance phenomenon can be prevented by providing a space between the test body and the metal plate, and a 100 mm front surface of the 400 mm × 400 mm metal plate is found.
The test piece was installed with a space of mm, and the metal plate and the test piece were not integrated so that the resonance phenomenon did not occur, and the reflection coefficient was measured by the free space time domain method. The reflection coefficient was calculated by comparing it with the reflection level of the metal plate alone and used as the electromagnetic wave absorption performance. Then, the reflection coefficient was measured by the free space timed-main-in method even for the structure in which an aluminum foil was put on the back surface of the test piece and the state where the resonance phenomenon occurred. With this method, it is possible to measure the radio wave absorption with higher effectiveness.

Hereinafter, regarding the non-combustible sound absorbing and radio wave absorbing ceiling plate of the present invention, including the comparison between the condition in which the resonance phenomenon is not caused and the condition in which the aluminum foil is attached to the back surface to cause the resonance phenomenon, the following Example 12 will be described. -19, Comparative Example 3 and Reference Example 1
2 will be described.

<Example 12> 41 wt% SiO ₂ , Ca
O36wt%, MgO6wt%, Al ₂ O ₃ 12wt%,
In addition, 89.75% by weight of steel slag rock wool having a fiber length of 100 to 500 μm and composed of 5% by weight of trace components such as Na ₂ O and K ₂ O, 1% by weight of beaten pulp dispersed in water and refined by a refiner, starch 5.5 wt%,
2.85 wt. Of attapulgite dispersed and disintegrated in water
%, 15% concentration polyacrylamide aqueous solution 0.2 wt%
(Solid content basis), 0.6 wt% aluminum sulfate, 1 wt% in water as a pretreatment, and stirred with a mixer for 2 minutes at a rotation speed of 200 rotations / minute. 0.1% by weight (solid content basis) of Gas Co., Ltd .; Zyrus is added and mixed, and dispersed by a mixer to prepare an aqueous slurry having a concentration of about 5% by weight. The slurry is made into paper by a Fourdrinier paper making machine and dehydrated and dried to produce a master plate. Further, the surface of this original plate was cut to obtain a panel N of an interior ceiling plate having a plate thickness of 12 mm and a bulk density of 0.4 g / cm ³ . Table 3 shows the strength, fire resistance, thermal conductivity, sound absorption coefficient, radio wave shielding performance, radio wave absorbing performance, etc. of panel N. As shown in Table 3, Example 12 has a good electromagnetic wave absorption performance of 6 dB or more both when the aluminum foil is attached to the back surface and when the aluminum foil is not attached to the back surface.

<Example 13> The carbon fiber blending ratio of Example 12 was 0.40 wt% and the rock wool blending ratio was 89.45 wt%. Panel O was obtained. The performance of panel O is also shown in Table 3. As shown in Table 3, Example 13 has a good electromagnetic wave absorption performance of 6 dB or more both when the aluminum foil is attached to the back surface and when the aluminum foil is not attached to the back surface.

Example 14 The carbon fiber content of Example 12 was 0.3 wt%, the rock wool content was 89.55 wt%, and the other conditions were the same as in Example 12 except that the interior ceiling plate was used. Panel P was obtained. Table 3 also shows the performance and the like of the panel P having a plate thickness of 9 mm whose surface is cut. As shown in Table 3, Example 14 has a good electromagnetic wave absorption performance of 6 dB or more both when the aluminum foil is attached to the back surface and when the aluminum foil is not attached to the back surface.

<Example 15> The carbon fiber content of Example 12 was 0.15 wt% and the rock wool content was 89.7 wt%. Panel Q was obtained. Table 3 also shows the performance and the like of the panel Q having a plate thickness of 15 mm whose surface is cut. As shown in Table 3, Example 15 has a good electromagnetic wave absorption performance of 6 dB or more both when the aluminum foil is attached to the back surface and when the aluminum foil is not attached to the back surface.

Example 16 The carbon fiber concentration of Example 12 was 0.3 wt%, the mixing ratio of rock wool was 89.55 wt%, and the other conditions were the same as in Example 12 except that the bulk density was 0.5. A panel R of an interior ceiling plate was obtained so as to have a weight of 5 g / cm ³ . Table 3 shows the performance of Panel R
Also shown in. As shown in Table 3, Example 16 has a good electromagnetic wave absorption performance of 6 dB or more both when the aluminum foil is attached to the back surface and when the aluminum foil is not attached to the back surface.

<Example 17> The carbon fiber length of Example 12 was 12 mm, the concentration was 0.18 wt%, the mixing ratio of rockwool was 89.67 wt%, and other conditions were the same as those of Example 12, and the interior was set. Ceiling panel S
Got The performance of the panel S is also shown in Table 3. As shown in Table 3, in Example 17, 6d was obtained even when the aluminum foil on the back surface was adhered or not.
It has a good electromagnetic wave absorption performance of B or higher.

<Example 18> Rock wool 86.1 wt
%, Gel 3 wt%, polyvinyl alcohol 7 wt%,
3 wt% of attapulgite, 0.2 wt% of polyacrylamide aqueous solution of 15% concentration (solid content basis), 0.6 wt% of aluminum sulfate, and 0.1 wt% of carbon fiber having a fiber length of 4 mm (Osaka Gas Co., Ltd .; Zyrus) Mix the mixture consisting of
A wt% concentration aqueous slurry is prepared. The slurry is made into paper by a Fourdrinier paper making machine and dehydrated and dried to produce a master plate. Furthermore, the surface of this original plate was cut to obtain a panel T of an interior ceiling plate having sufficient strength as an interior ceiling plate. Table 4 summarizes the performance of the panel T such as strength, fire resistance, thermal conductivity, sound absorption coefficient, radio wave shielding performance, and radio wave absorption performance. As shown in Table 4,
In Example 18, good electromagnetic wave absorption performance of 6 dB or more was obtained both when the aluminum foil was attached to the back surface and when the aluminum foil was not attached to the back surface.

Example 19 Rock wool 61.1 wt
%, Gel 3 wt%, polyvinyl alcohol 7 wt%,
Attapulgite 3 wt%, 15% polyacrylamide aqueous solution 0.2 wt% (solid content basis), aluminum sulfate 0.6 wt%, aluminum hydroxide 25 wt%,
Carbon fiber with a fiber length of 4 mm (Osaka Gas Co., Ltd.)
(Manufactured by Zyrus), a mixture of 0.1 wt% (solid content basis) is dispersed with a mixer to prepare an aqueous slurry having a concentration of about 5 wt%. The slurry is made into paper by a Fourdrinier paper making machine and dehydrated and dried to produce a master plate. Further, the surface of this original plate was cut to obtain a panel U of an interior ceiling plate having sufficient strength as an interior ceiling plate. Table 4 summarizes the performance of the panel U such as strength, fire resistance, thermal conductivity, sound absorption coefficient, radio wave shielding performance, and radio wave absorbing performance. As shown in Table 4, Example 19 has a good electromagnetic wave absorption performance of 6 dB or more both when the aluminum foil is attached to the back surface and when the aluminum foil is not attached to the back surface.

Comparative Example 3 Rock wool 89.85 wt
%, Gel 1 wt%, starch 5.5 wt%, attapulgite 2.85 wt%, 15% concentration polyacrylamide aqueous solution 0.2 wt% (solid content basis), aluminum sulfate 0.6 wt% is mixed with a mixer and dispersed. 5w
An aqueous slurry with t% concentration is prepared. The slurry is made into paper by a Fourdrinier paper making machine and dehydrated and dried to produce a master plate. Further, the surface of this original plate was cut to obtain a panel V of an interior ceiling plate having sufficient strength as an interior ceiling plate. Table 4 shows the strength, fireproofness, thermal conductivity, sound absorption coefficient, radio wave shielding performance, radio wave absorbing performance, etc. of panel V. As shown in Table 4,
In Comparative Example 3, the electromagnetic wave absorption performance is not exhibited when the aluminum foil is attached to the back surface and when the aluminum foil is not attached to the back surface.

Reference Example 1 Rockwool 89.80 wt
%, Gel 1 wt%, starch 5.5 wt%, attapulgite 2.85 wt%, 15% concentration polyacrylamide aqueous solution 0.2 wt% (solid content basis), aluminum sulfate 0.6 wt%, carbon fiber with fiber length 4 mm (Osaka Gas Co., Ltd .; Zyrus) A mixture of 0.05 wt% is dispersed by a mixer to prepare an aqueous slurry having a concentration of about 5 wt%. The slurry is made into paper by a Fourdrinier paper making machine and dehydrated and dried to produce a master plate. Further, the surface of this original plate was cut to obtain a panel W of an interior ceiling plate having sufficient strength as an interior ceiling plate. Table 4 summarizes the performance of the panel W such as strength, fire resistance, thermal conductivity, sound absorption coefficient, radio wave shielding performance, and radio wave absorbing performance. As shown in Table 4, in Reference Example 1, the desired electromagnetic wave absorption performance was obtained when the aluminum foil was attached to the back surface, but sufficient electromagnetic wave absorption performance was not obtained when the aluminum foil on the back surface was not attached.

Reference Example 2 Rockwool 89.25 wt
%, Gel 1 wt%, starch 5.5 wt%, attapulgite 2.85 wt%, 15% concentration polyacrylamide aqueous solution 0.2 wt% (solid content basis), aluminum sulfate 0.6 wt%, carbon fiber with fiber length 4 mm (Osaka Gas Mixing of 0.6 wt% manufactured by Zyrus Co., Ltd. is dispersed by a mixer to prepare an aqueous slurry having a concentration of about 5 wt%. The slurry is made into paper by a Fourdrinier paper making machine and dehydrated and dried to produce a master plate. Further, the surface of this original plate was cut to obtain a panel X of an interior ceiling board having sufficient strength as an interior ceiling board. The performance of panel X such as strength, fire resistance, thermal conductivity, sound absorption coefficient, radio wave shielding performance, and radio wave absorption performance are summarized in Table 4. As shown in Table 4, in Reference Example 2, when the aluminum foil was attached to the back surface and when the aluminum foil was not attached to the back surface, sufficient electromagnetic wave absorption performance of 6 dB or more was not obtained.

[0072]

[Table 3]

[0073]

[Table 4]

<Evaluation and Measurement Methods in Tables 3 and 4> Bending Strength: According to JIS A 1408 (No. 5 test piece) method. Thermal resistance: According to JIS A 1420 method. Fireproof performance: According to JIS A 1321 method. Sound absorption coefficient: According to JIS A 1409 (reverberation room) method. Radio wave shielding performance: A test body having a thickness of 9 to 15 mm and length and width of 400 mm × 400 mm for each test is installed between the radio wave transmitting antenna and the receiving antenna, and the transmission level is measured by the time domain method. The transmission coefficient was calculated as a radio wave shielding performance by comparing with the transmission level when the test body was not installed. Radio wave absorption performance: In order to prevent the resonance phenomenon from reflected radio waves and measure only the radio wave absorption performance due to the internal loss of the test body itself, a 100 mm space is provided in front of a metal plate measuring 400 mm x 400 mm in length and width. A test body with a thickness of 9 to 15 mm and a length and width of 400 mm x 400 mm is installed for each test, and the reflection coefficient is measured by the free space time domain method without the resonance phenomenon caused by radio wave reflection. The reflection coefficient was calculated by comparing it with the reflection level of the metal plate alone and used as the electromagnetic wave absorption performance. Next, the reflection coefficient was measured by the free space time domain method for a test piece with a structure in which an aluminum foil was attached to the back surface of the test piece, in which resonance phenomenon due to radio wave reflection occurred.

<< Comparison of Examples and Comparative Examples in Tables 3 and 4 >> Regarding the bending strength, all show the suitability value as an interior ceiling board. 2. Regarding heat resistance, they all show sufficient heat insulating properties, and there is no significant difference. 3. Regarding fire resistance, Examples 12 to 17 and Example 1
9 and Comparative Example 3 and Reference Examples 1 and 2 were nonflammable, and Example 18 was quasi nonflammable and passed. 4. Regarding the sound absorption coefficient, in each of Examples 12 to 19, Comparative Example 3 and Reference Examples 1 and 2, an appropriate sound absorption coefficient is shown and there is no significant difference. 5. The radio wave shielding performance is the same as that in Example 12 under the condition that no aluminum foil is used.
˜19 and Reference Examples 1 and 2 show a shielding performance of 2 to 6.8 dB, but they do not have sufficient performance as a general radio wave shielding material. Comparative Example 3 shows almost no radio wave shielding performance. 6. Regarding the radio wave absorption performance, in Examples 12 to 19, both in the case where the back surface was integrated with the aluminum foil and in the case where the back surface was not integrated with the aluminum foil, 2.45 was obtained.
It shows 6 to 9 dB at GHz and 6 to 9 dB at 5.1 GHz, and is 2.4 used for a wireless LAN system.
In wireless communication in an office or the like in the GHz band and the 5 GHz band, both of 6 dB or more, which is a sufficient absorption performance, are satisfied as a communication failure countermeasure. Therefore, Example 1
It has been shown that under the conditions of carbon fiber combination of 2 to 19, good electromagnetic wave absorption performance can be obtained even when the aluminum foil is not integrated on the back surface. On the other hand, in the case of Comparative Example 3 in which carbon fiber as a conductive substance is not mixed,
Absorption performance is not obtained. Also, in Reference Example 1,
Since the carbon fiber content is low, the desired radio wave absorption performance is exhibited when aluminum foil is attached to the back side due to the addition of radio wave loss due to resonance, but sufficient absorption performance is not shown when the aluminum foil is not attached to the back side. In Reference Example 2, since the carbon fiber is highly mixed, it is not affected by radio wave reflection even if the aluminum foil is not attached to the back surface, and does not exhibit sufficient absorption performance.

Example 20 In the ceiling board described in Reference Example 1 above, the fiber length of 0.
Each ceiling board was obtained by roller-coating a vinyl acetate emulsion paint (polyvinyl acetate PC coat) containing 7 mm pitch-based carbon fibers in various blending amounts at a rate of 625 g / m ² . Table 5 shows the compounding amounts of the carbon fibers on the front surface and the back surface (in the PC coating) of each ceiling plate and the radio wave absorbing performance thereof. The radio wave absorption performance was measured by the same method as in Examples 12-19.

[0077]

[Table 5]

From the results shown in Table 5, the carbon fiber content on the surface (particularly referred to as "CF1") was 0.10 wt%.
If it is above, very good electromagnetic wave absorption performance can be obtained without adding carbon fiber to the PC coat.
When the content of F1 is 0.08 wt% or less, sufficient radio wave absorption performance cannot be obtained with a structure in which no aluminum foil is attached. On the other hand, even if CF1 has a low compounding amount, PC in which a larger amount of carbon fiber is compounded
It can be seen that the electromagnetic wave absorption performance is remarkably improved by applying the coat (the compounding amount in the PC coat is particularly referred to as “CF2”) to the back surface.

Particularly, by devising the blending amount of both, the absorption performance of 6 dB or more, which is the absorption performance suitable for the wireless communication application (wireless LAN), can be obtained. In particular, the carbon fiber compounding amount (CF1) of the front side ceiling plate is 0.04 wt.
% To 0.08 wt%, compounding amount in CF coating (CF2)
Is 1.0 wt% to 15.0 wt%, the above-mentioned suitable absorption performance is obtained.

[0080]

As described above, the non-combustible sound absorbing and electromagnetic wave absorbing ceiling plate of the present invention is lightweight, has a quasi non-combustible to non-combustible fireproof property, and has both sound absorbing property, heat insulating property, and electromagnetic wave absorbing property, and is low in Since it has a sufficient bending strength at a cost, it has an effect as a non-combustible sound absorbing and electromagnetic wave absorbing ceiling plate which can suitably meet various structural needs of buildings and various functional needs as building members.

Further, in the above-mentioned non-combustible sound absorbing and electromagnetic wave absorbing ceiling plate, by adopting a laminated structure of a layer not containing carbon fiber and a two-layer containing carbon fiber, a design effect can be obtained on the interior surface after construction. The added interior ceiling plate can be obtained.

Furthermore, when a non-combustible sound absorbing and electromagnetic wave absorbing ceiling plate with a metal foil is adopted, in addition to the electromagnetic wave absorbing effect in which the electromagnetic wave absorption due to the resonance phenomenon of the reflected electromagnetic wave is additionally improved, the effect of additionally improving the electromagnetic wave shielding property is obtained. Have.

The non-combustible sound absorbing and electromagnetic wave absorbing ceiling plate of the present invention is
By setting the mixing ratio of the carbon fibers having a fiber length of 1 to 30 mm to 0.08 to 0.4 wt%, excellent radio wave absorption performance can be obtained without adding radio wave absorption due to a resonance phenomenon from reflected radio waves. In particular, there is an effect that a preferable radio wave absorption performance for wireless communication applications (wireless LAN), especially a radio wave absorption performance of 6 dB or more can be obtained.

Furthermore, an organic coating composition is used in which the blending ratio of the carbon fibers having a fiber length of 1 to 30 mm is 0.04 to 0.08 wt% and the back surface thereof is blended with a larger amount of carbon fibers than the blending amount of the carbon fibers. By applying it, it is possible to obtain excellent electromagnetic wave absorption performance, and particularly preferable absorption performance for wireless communication applications.

Claims (3)

[Claims] 1. Rock wool 67 to 92 wt%, beaten pulp 0.5 to 8 wt%, and a binder 2-1 made of an organic resin.
3 wt%, coagulant 0.15 to 1 wt%, natural mineral fiber 0.5 to 10 wt% and carbon fiber having a fiber length of 1 to 30 mm 0.02 to 1 wt% were mixed to obtain an aqueous dispersion slurry by wet papermaking. Thickness of 1 to 30 mm
A radio wave absorbing ceiling board for indoor wireless communication obtained by attaching a metal foil to the back surface of the board. 2. Rock wool 67 to 92 wt%, beaten pulp 0.5 to 8 wt%, and a binder 2-1 made of an organic resin.
3 wt%, coagulant 0.15 to 1 wt%, natural mineral fiber 0.5 to 10 wt% and carbon fiber having a fiber length of 1 to 30 mm 0.08 to 0.4 wt% were mixed to prepare a water-dispersed slurry, which was wet-processed. 1-30 obtained by
mm ceiling plate for indoor wireless communication. 3. A method for preventing indoor wireless communication failure using the ceiling plate according to claim 1 or 2.